@inproceedings{lee-etal-2026-latent,
title = "Latent Task Embedding: Geometric Expansion for Single-Path Multi-Task {PEFT}",
author = "Lee, Junhyun and
Song, Seoha and
Gowda, Dhananjaya",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.emnlp-main.2649/",
pages = "60275--60293",
ISBN = "979-8-89176-459-0",
abstract = "Parameter-efficient fine-tuning (PEFT) typically relies on additive weight perturbation. However, in dynamic deployment environments like multi-tenant cloud serving or mobile edge devices, additive methods force a dilemma: merge weights and lose task-switching flexibility, or remain unmerged and suffer severe parallel-branching latency. To break this bottleneck, we propose Latent Task Embedding (LatTE), which shifts the PEFT design axis to geometric expansion. Instead of perturbing frozen parameters, LatTE concatenates a task-specific auxiliary embedding to the input and expands the corresponding weight matrices. This structural fusion ensures the forward pass remains a single, optimized matrix multiplication, bypassing the routing overhead of unmerged adapters. Furthermore, LatTE natively supports router-free, intra-batch multi-tasking by isolating tasks into distinct subspaces controlled via binary masking. Extensive evaluations across 1B to 14B parameter models demonstrate that LatTE matches highly optimized baselines like LoRA, while raising throughput by 1.7{\texttimes} over routed multi-adapter LoRA under heterogeneous-task batching."
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<abstract>Parameter-efficient fine-tuning (PEFT) typically relies on additive weight perturbation. However, in dynamic deployment environments like multi-tenant cloud serving or mobile edge devices, additive methods force a dilemma: merge weights and lose task-switching flexibility, or remain unmerged and suffer severe parallel-branching latency. To break this bottleneck, we propose Latent Task Embedding (LatTE), which shifts the PEFT design axis to geometric expansion. Instead of perturbing frozen parameters, LatTE concatenates a task-specific auxiliary embedding to the input and expands the corresponding weight matrices. This structural fusion ensures the forward pass remains a single, optimized matrix multiplication, bypassing the routing overhead of unmerged adapters. Furthermore, LatTE natively supports router-free, intra-batch multi-tasking by isolating tasks into distinct subspaces controlled via binary masking. Extensive evaluations across 1B to 14B parameter models demonstrate that LatTE matches highly optimized baselines like LoRA, while raising throughput by 1.7× over routed multi-adapter LoRA under heterogeneous-task batching.</abstract>
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%0 Conference Proceedings
%T Latent Task Embedding: Geometric Expansion for Single-Path Multi-Task PEFT
%A Lee, Junhyun
%A Song, Seoha
%A Gowda, Dhananjaya
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-459-0
%F lee-etal-2026-latent
%X Parameter-efficient fine-tuning (PEFT) typically relies on additive weight perturbation. However, in dynamic deployment environments like multi-tenant cloud serving or mobile edge devices, additive methods force a dilemma: merge weights and lose task-switching flexibility, or remain unmerged and suffer severe parallel-branching latency. To break this bottleneck, we propose Latent Task Embedding (LatTE), which shifts the PEFT design axis to geometric expansion. Instead of perturbing frozen parameters, LatTE concatenates a task-specific auxiliary embedding to the input and expands the corresponding weight matrices. This structural fusion ensures the forward pass remains a single, optimized matrix multiplication, bypassing the routing overhead of unmerged adapters. Furthermore, LatTE natively supports router-free, intra-batch multi-tasking by isolating tasks into distinct subspaces controlled via binary masking. Extensive evaluations across 1B to 14B parameter models demonstrate that LatTE matches highly optimized baselines like LoRA, while raising throughput by 1.7× over routed multi-adapter LoRA under heterogeneous-task batching.
%U https://aclanthology.org/2026.emnlp-main.2649/
%P 60275-60293
Markdown (Informal)
[Latent Task Embedding: Geometric Expansion for Single-Path Multi-Task PEFT](https://aclanthology.org/2026.emnlp-main.2649/) (Lee et al., EMNLP 2026)
ACL